Hepatitis B virus genotype distribution and genotype-specific BCP/preCore substitutions in acute and chronic infections in Argentina

Characterization of mutations in hepatitis B virus DNA isolated from Japanese HBsAg-positive blood donors in 2021 and 2022

Missense mutations in certain small envelope proteins diminish the efficacy of antibodies. Consequently, tracking the incidence and types of vaccine-escape mutations (VEMs) was crucial both before and after the introduction of universal hepatitis B vaccination in Japan in 2016. In this study, we isolated hepatitis B virus (HBV) DNA from 58 of 169 hepatitis B surface antigen (HBsAg)-positive blood samples from Japanese blood donors and determined the nucleotide sequence encoding the small envelope protein. DNA from six (10%) of the samples had VEMs, but no missense mutations, such as G145R, were detected. Complete HBV genome sequences were obtained from 29 of the 58 samples; the viral genotype was A1 in one (3%), A2 in three (10%), B1 in nine (31%), B2 in five (17%), B4 in one (3%), and C2 in 10 (34%) samples. Tenofovir-resistance mutations were detected in two (7%) samples. In addition, several core promoter mutations, such as 1762A>T and 1764G>A, and a precore nonsense mutation, 1986G>A, which are risk factors for HBV-related chronic liver disease, were detected. These findings provide a baseline for future research and highlight the importance of ongoing monitoring of VEMs and drug resistance mutations in HBV DNA from HBsAg-positive blood donors without HBV antibodies.

Acute and chronic HBV infection in central Argentina: High frequency of sub-genotype F1b, low detection of clinically relevant mutations and first evidence of HDV

Introduction

Genomic analysis of hepatitis B virus (HBV) identifies phylogenetic variants, which may lead to distinct biological and clinical behaviors. The satellite hepatitis D virus (HDV) may also influence clinical outcomes in patients with hepatitis B. The aim of this study was to investigate HBV genetic variants, including clinically relevant mutations, and HDV infection in acute and chronic hepatitis B patients in central Argentina.

Methods

A total of 217 adult HBV infected patients [acute (AHB): n = 79; chronic (CHB): n = 138] were studied; 67 were HBV/human immunodeficiency virus (HIV) coinfected. Clinical and demographic data were obtained from medical records. Serological markers were determined. Molecular detection of HBV and HDV was carried out by RT-Nested PCR, followed by sequencing and phylogenetic analysis.

Results

Overall, genotype (gt) F [sub-genotype (sgt) F1b] was the most frequently found. In AHB patients, the gts/sgts found were: F1b (74.7%) > A2 (13.9%) > F4 (7.6%) > C (2.5%) > A1 (1.3%). Among CHB patients: F1b (39.1%) > A2 (23.9%) > F4 (18.2%) > D (9.4%) > C and F6 (3.6% each) > A1, A3 and B2 (0.7% each). The distribution of sgt A2 and gt D was significantly different between HBV mono and HBV/HIV coinfected patients [A2: 15.9% vs. 35.7% (p < 0.05), respectively and D: 14.6% vs. 1.8% (p < 0.05), respectively]. Mutation frequency in basal core promoter/pre-Core (BCP/pC) region was 35.5% (77/217) [AHB: 20.3% (16/79), CHB: 44.2% (61/138)]. In the open reading frame (ORF) S, mutations associated with vaccine escape and diagnostic failure were detected in 7.8% of the sequences (17/217) [AHB: 3.8% (3/79), CHB: 10.1% (14/138)]. ORF-P amino acid substitutions associated with antiviral resistance were detected in 3.2% of the samples (7/217) [AHB: 1.3% (1/79), CHB 4.3%, (6/138)]. The anti-HDV seropositivity was 5.2% (4/77); one sample could be sequenced, belonging to gt HDV-1 associated with sgt HBV-D3.

Discussion

We detected an increase in the circulation of genotype F in Central Argentina, particularly among AHB patients, suggesting transmission advantages over the other genotypes. A low rate of mutations was detected, especially those with antiviral resistance implications, which is an encouraging result. The evidence of HDV circulation in our region, reported for the first time, alerts the health system for its search and diagnosis.

Molecular and biological characterization of hepatitis B virus subgenotype F1b clusters: Unraveling its role in hepatocarcinogenesis

Hepatitis B virus (HBV) subgenotype F1b infection has been associated with the early occurrence of hepatocellular carcinoma in chronically infected patients from Alaska and Peru. In Argentina, however, despite the high prevalence of subgenotype F1b infection, this relationship has not been described. To unravel the observed differences in the progression of the infection, an in-depth molecular and biological characterization of the subgenotype F1b was performed. Phylogenetic analysis of subgenotype F1b full-length genomes revealed the existence of two highly supported clusters. One of the clusters, designated as gtF1b Basal included sequences mostly from Alaska, Peru and Chile, while the other, called gtF1b Cosmopolitan, contained samples mainly from Argentina and Chile. The clusters were characterized by a differential signature pattern of eight nucleotides distributed throughout the genome. In vitro characterization of representative clones from each cluster revealed major differences in viral RNA levels, virion secretion, antigen expression levels, as well as in the localization of the antigens. Interestingly, a differential regulation in the expression of genes associated with tumorigenesis was also identified. In conclusion, this study provides new insights into the molecular and biological characteristics of the subgenotype F1b clusters and contributes to unravel the different clinical outcomes of subgenotype F1b chronic infections.

Common hepatitis B virus genotypes among blood donors in Lagos, Nigeria

BACKGROUND

Hepatitis B virus (HBV) infection is one of the public health diseases causing global health problems. It is a leading cause of cirrhosis and hepatocellular carcinoma. Blood transfusion is a major route of its transmission and screening of blood is suboptimal in our environment. Occult HBV infection describes the presence of HBV DNA in blood or liver tissue in patients who are hepatitis B surface antigen (HBsAg) seronegative. This study documented the common genotypes of HBV a blood-borne infection in the population of blood donors in Lagos.

METHODS

This was a cross-sectional study carried out at the blood donor clinics of ten Lagos State Government-owned hospitals in Lagos State. A total of 1400 participants were recruited consecutively from November 2020 to June 2021. All participants' samples were screened using Diaspot Rapid Test Kit (RTK) and Dialabenzyme enzyme-linked immunosorbent assay (ELISA) kit. Furthermore, some of the plasma samples were used for HBV DNA extraction and genotyping using the real time-polymerase chain reaction. Statistical analysis was carried out using the Statistical Package for the Social Sciences (SPSS) software version 26 and P value was considered significant at ≤0.05.

RESULTS

The sero-prevalence of HBsAg using RTK and ELISA was 19.9% and 22.4%, respectively. The prevalence of occult HBV infection was 5.2%. A total of 278 and 313 HBsAg RTK and ELISA positive samples were obtained, respectively. HBV genotype result had A (46.6%) as the most prevalent followed closely by B (44.7%), E (23.8%), D (20.9%) and C (11.2%).

CONCLUSION

HBV infection has a high prevalence among blood donors. ELISA is a more sensitive screening tool and its use should be advocated nationally. HBV genotype A is the most prevalent genotype from our study.

Viral Kinetics of an Acute Hepatitis B Virus Subgenotype F1b Infection in a Mexican Subject

Content available: Author Interview and Audio Recording.

Biological Characterization of Hepatitis B virus Genotypes: Their Role in Viral Replication and Antigen Expression

Hepatitis B virus (HBV) inter-host evolution has resulted in genomic diversification reflected in the existence of nine genotypes (A-I) and numerous subgenotypes. There is growing evidence that genotypes influence HBV natural history, clinical outcomes, and treatment response. However, the biological characteristics underlying these differences have not yet been established. By transfecting HuH-7 cells with unit-length constructs of genotypes A2, B2, C1, D1, and F1b, we identified major differences in HBV replicative capacity and antigen expression across genotypes. Genotypes B2 and F1b showed a 2-fold increase in cccDNA levels compared to the other genotypes (p<0.005). Genotype A2 expressed the lowest pgRNA levels, with a 70-fold decrease in relation to the other genotypes (p<0.0001), while genotype B2 showed the lowest Precore RNA levels, with a 100-fold reduction compared to genotype A2 (p<0.0001). The highest intracellular HBV DNA levels were observed for genotype B2 and the lowest for genotypes A2 and C1 (p<0.0001). Regarding antigen expression, genotype F1b secreted the highest HBsAg levels and genotype D1 the lowest (p<0.0001), while genotypes A2 and B2 showed the highest intracellular HBsAg levels (p<0.0001). Interestingly, genotype C1 secreted the highest HBeAg levels, while genotype A2 showed the highest intracellular levels (p<0.0001). Finally, the analysis of the intra/extracellular antigen ratios revealed that most genotypes retained intracellularly 5-20% of the antigens, except the genotype A2 that retained 50% of the total expressed antigens. In conclusion, this study provides new insights into the biological characteristics of HBV genotypes, being the first study to comparatively analyze European (A and D) and Asian (B and C) genotypes with the Latin American (F) genotype. The differences in HBV replication and antigen expression might contribute to understand the differential role of genotypes in pathogenesis.

Drug-resistant and immune-escape hepatitis B virus mutants, occult hepatitis B infection and coinfections in public hospital patients from Argentina

Argentina exhibits low serological prevalence for Hepatitis B virus (HBV); however, occult hepatitis B infection (OBI) has been reported in blood donors, Amerindians and individuals coinfected with hepatitis C virus (HCV), and/or human immunodeficiency virus (HIV). The aim of this study was to analyze the genetic diversity of HBV and to evaluate serological marker associations and coinfections with HCV and HIV in patients attending and treated in a public hospital in the province of Buenos Aires, Argentina. A total of 189 HBV reactive samples (HBsAg and/or anti-HBc) were analyzed for HBV DNA characterization. All reactive samples were tested for anti-HCV and HIV-antigen/antibody using CMIA assays. Thirty-six samples exhibited detectable HBV DNA, 7 of which were OBI. HBV sequences were classified as subgenotypes A1, A2, B2, D3, F1b, F3 and F4. Mutations related to the ability to escape the host's immune response, resistance to antiviral therapy and progression to disease were found in patients, partly due to the variable sensitivity of HBsAg, the reverse transcriptase, the basal core promoter and the preCore. HCV and HIV prevalence was 10% and most of the genotypes found in the sequences were genotype 1 and B/F recombinant subtype, respectively. Of the total samples analyzed, 7 exhibited coinfections. This study shows the frequency of OBI, subgenotype distribution, HBV mutations and coinfections, which may have important clinical implications in public hospital patients. Planned prevention, detection and treatment adherence are needed to reduce transmission and morbidity in vulnerable populations.

Hepatitis B virus American genotypes: Pathogenic variants ?

Hepatitis B virus (HBV) chronic infection is responsible for almost 900.000 deaths each year, due to cirrhosis or hepatocellular carcinoma (HCC). Ten HBV genotypes have been described (A-J). HBV genotype F and H circulate in America. HBV genotypes have been further classified in subgenotypes. There is a strong correlation between the genetic admixture of the American continent and the frequency of genotypes F or H: a high frequency of these genotypes is found in countries with a population with a higher ratio of Amerindian to African genetic admixture. The frequency of occult HBV infection in Amerindian communities from Latin America seems to be higher than the one found in other HBV-infected groups, but its association with American genotypes is unknown. There is growing evidence that some genotypes might be associated with a faster evolution to HCC. In particular, HBV genotype F has been implicated in a frequent and rapid progression to HCC. However, HBV genotype H has been associated to a less severe progression of disease. This study reviews the diversity and frequency of autochthonous HBV variants in the Americas and evaluates their association to severe progression of disease. Although no significant differences were found in the methylation pattern between different genotypes and subgenotypes of the American types, basal core promoter mutations might be more frequent in some subgenotypes, such as F1b and F2, than in other American subgenotypes or genotype H. F1b and probably F2 may be associated with a severe presentation of liver disease as opposed to a more benign course for subgenotype F4 and genotype H. Thus, preliminary evidence suggests that not all of the American variants are associated with a rapid progression to HCC.

Long-term evolution of hepatitis B virus genotype F: Strong association between viral diversification and the prehistoric settlement of Central and South America

The genotype F (HBV-F) is an autochthonous Native American strain of the hepatitis B virus. In this study, we reconstruct the HBV-F long-term evolution under a hypothesis of co-divergence with humans in Central and South America, since their entry into the region 14.5-16 thousand years ago. The Bayesian phylogeographic reconstruction supported a virus-host co-expansion; however, two evolutionary scenarios would have been present. Whereas subgenotype F1 spreads along a Pacific coastal route and would have evolved associated with Central American and Andean cultures from the west of the continent, subgenotypes F2-F6 spread along the Atlantic coastline and inner pathways associated with communities inhabiting the tropical forest lowlands. Then, we propose a model for HBV-F evolution in which the selection of differential biological characteristics in these two main groups would be related to their evolution in host populations with different genetic backgrounds and dissimilar demographic conditions.

Analysis of genomic-length HBV sequences to determine genotype and subgenotype reference sequences

Hepatitis B virus (HBV) is a diverse, partially double-stranded DNA virus, with 9 genotypes (A-I), and a putative 10th genotype (J), characterized thus far. Given the broadening interest in HBV sequencing, there is an increasing requirement for a consistent, unified approach to HBV genotype and subgenotype classification. We set out to generate an updated resource of reference sequences using the diversity of all genomic-length HBV sequences available in public databases. We collated and aligned genomic-length HBV sequences from public databases and used maximum-likelihood phylogenetic analysis to identify genotype clusters. Within each genotype, we examined the phylogenetic support for currently defined subgenotypes, as well as identifying well-supported clades and deriving reference sequences for them. Based on the phylogenies generated, we present a comprehensive set of HBV reference sequences at the genotype and subgenotype level. All of the generated data, including the alignments, phylogenies and chosen reference sequences, are available online (https://doi.org/10.6084/m9.figshare.8851946) as a simple open-access resource.

Epidemiology of hepatitis B and C virus infection in Central West Argentina

Little information is available regarding the prevalence of viral hepatitis in Central West Argentina. This study aims to give new information regarding HBV and HCV prevalence, genotypes, and risk factors in Central West Argentina and the suitability of dried blood spot (DBS) sampling for HBV and HCV screening.

METHODS

A total of 622 individuals were included; the mean age was 36.6 ± 14.3 years and 55.4% were females. HBV and HCV markers were detected using serological and molecular analysis, and risk factors were evaluated using statistical analysis.

RESULTS

Using serum samples, the HBsAg prevalence was 1.8%, the rate of HBV exposure (anti-HBc positivity) was 5.3%, and the rate of HBV immunity was 34.9%. HBV DNA was found in four out of 11 HBsAg⁺ samples, and the viruses in three of these samples were classified as genotypes A1, A2 and F2a. Multivariate analysis showed that anti-HBs positivity was associated with the level of schooling and history of HBV vaccination. The anti-HCV prevalence was 2.6%, and HCV RNA was found in 11 samples, seven of which contained viruses of genotypes 1a (n = 2), 1b (n = 3) and 2 (n = 2). The sensitivity of the DBS assay for HBsAg, anti-HBc, and anti-HCV was 100%, 66.6%, and 75%, respectively, and the specificity was above 98% for all markers when compared to serum.

CONCLUSION

A low rate of HBV immunity was observed, demonstrating the importance of HBV vaccination. High HCV prevalence was found, and HCV 1b was closely related to other Argentinian isolates. Finally, the performance of DBS testing in this population needs more optimization to increase its sensitivity and specificity.

The genetic variability of hepatitis B virus subgenotype F1b precore/core gene is related to the outcome of the acute infection

AIM

To assess the association of viral and host genetic variability with the outcome of acute infection with hepatitis B virus subgenotype F1b (HBV/F1b).

METHODS

The cohort consisted of 26 patients with acute HBV/F1b infection who exhibit different outcomes: spontaneous resolution (n = 10), progression to chronic hepatitis (n = 10) and acute liver failure (n = 6). HLA SNPs (rs3077, rs9277542, rs2856718 and rs7453920) were determined. The S gene and core promoter/precore/core region were direct sequenced, and this latter region was also ultra-deep sequenced. Mean number of mutations, mutation rate, Shannon entropy, positive selection sites and mutational patterns of quasispecies were compared between groups.

RESULTS

HLA SNPs were associated with spontaneous resolution or progression to chronic hepatitis, but not with the development of acute liver failure. The mean number of mutations in the S gene was similar among the three groups. Patients with spontaneous resolution had the lowest number of mutations, mutation rates and Shannon entropy values in the precore/core compared to the other two groups. Ten positive selection sites mapped on HLA-restricted epitopes were related to progression to chronic hepatitis and acute liver failure. Mutations T1753C, A1762T, G1764A, C1766T, T1768A G1896A, G2092T and T2107C were associated with acute liver failure and progression to chronic hepatitis.

CONCLUSION

Highly heterogeneous and complex HBV precore/core carrying specific point mutations, combined with the host HLA background, were associated with a worse clinical outcome of acute HBV/F1b infection.

Hepatitis B Virus X Gene Differentially Modulates Subgenotype F1b and F4 Replication

Hepatitis B virus (HBV) is classified into ten genotypes and numerous subgenotypes (sgt). In particular, sgt F1b and sgt F4, native of Latin America, have been associated with differences in clinical and virological characteristics. Hepatitis B virus X protein (HBx) is a multifunctional regulatory protein associated with the modulation of viral transcription and replication. In this work, we analyzed the role of the X gene and the encoded X protein in sgtF1b and sgtF4 replication. Transfection with HBx deficient genomes revealed remarkable differences in the replicative capacity of sgtF1b and sgtF4 mutants. The silencing of HBx increased sgtF1b X(-) transcription and replication by more than 2.5 fold compared to the wild type variant, while it decreased sgtF4 X(-) transcription and replication by more than 3 fold. Trans-complementation of HBx restore sgtF1b and sgtF4 wild type transcription and replication levels. In addition, transfection with chimeric variants, carrying wild type (F1b/XF4 and F4/XF1b) or mutated (F1b/X(-)F4 and F4/X(-)F1b) X gene of one sgt in the backbone of the other sgt, showed that the nucleotide sequence of the X gene, that includes regulatory elements that modulate pgRNA transcription, was responsible for the disparity observed between sgtF1b X(-) and sgtF4 X(-). These results showed that sgtF1b and sgtF4 X gene play a central role in regulating HBV transcription and replication, which eventually lead to a common purpose, to reach wild type replication levels of sgtF1b and sgtF4 viruses.

Molecular epidemiology of hepatitis B virus in Paraguay

Hepatitis B virus (HBV) infection is a leading cause of severe chronic liver disease worldwide. The HBV epidemiology in Latin American countries is complex and the data is still scanty and fragmentary. The aim of this study was to investigate the distribution of HBV genotypes in Paraguay and to estimate the viral population dynamic and spread pattern of the main phylogenetic group. To this end, partial and complete genome sequences were obtained from 60 blood donor candidates and analysed by phylogenetic and Bayesian phylodynamic approaches. The phylogenetic analysis based on sequences of partial Polymerase/Pre-S1 overlapping region showed a predominance of the Native American subgenotype F4 (81.7%), the presence of the European subgenotypes A2 (1.7%) and D3 (8.3%), the African subgenotype A1 (3, 5%) and the Asian subgenotypes B2 (1.7%) and C2 (1.7%). The distribution of HBV genotypes was in accordance with the ethnic composition of the population. The phylogeographic analysis of subgenotype F4 complete genomes suggests that this lineage emerged and spread in the last 300 years. Paraguay was the most probable location of the common ancestor. The lineage diverged into two main clades and spread to neighbor regions, mainly Bolivia and Northwest Argentina, and Buenos Aires. The phylogeny showed a scanty geographical structure and a complex migratory pattern. In conclusion, the HBV genotypes circulating in Paraguay reflect the ethnic origin of the population. The distribution of genotypes and the phylogeographic reconstruction showed the impact of both global and local migrations in shaping the HBV molecular epidemiology in the region.

Analysis of fitness differences of hepatitis B virus genotypes D and F using a cotransfection assay

Hepatitis B virus (HBV) circulates as a collection of genetically related variants that evolve throughout the chronic infection. Those viral variants that have the greatest fitness are fixed. We recently showed different fitness for HBV variants involved in two epidemiological situations. To understand these fitness differences better, we determined the levels of extracellular HBV DNA, the synthesis of HBV DNA intermediates, and the expression of HBeAg and HBsAg in transfection and cotransfection assays. Our results show that for the subgenotype (sgt) D1, which has an 8-nucleotide deletion (sgtD1del) and exhibits lower fitness, the levels of extracellular DNA and intracellular replicative intermediates were much lower than with sgtD1wt or sgtD1mut (G1896A), which had higher fitness. In addition, in the cotransfection assay, sgtD1del inhibited sgtD1mut but not sgtD1wt replication. We also found that sgtF1b, which exhibits higher fitness, produces significantly higher levels of both extracellular DNA and intracellular replicative intermediates than does the lower-fitness sgtF4. These results demonstrate a relationship between fitness and the replicative ability of the HBV genome in the transfection assay. In addition, the data obtained by cotransfecting cells with sgtD1del and sgtD1mut provide new information about the impact of simultaneous replication of two viral variants in the same cell system on HBV replication.

HBV subgenotypes F1b and F4 replication induces an incomplete autophagic process in hepatocytes: Role of BCP and preCore mutations

Hepatitis B virus (HBV) genotypes and mutants have been associated with differences in clinical and virological characteristics. Autophagy is a cellular process that degrades long-lived proteins and damaged organelles. Viruses have evolved mechanisms to alter this process to survive in host cells. In this work, we studied the modulation of autophagy by the replication of HBV subgenotypes F1b and F4, and the naturally occurring mutants BCP and preCore. HBV subgenotypes F1b and F4 replication induced accumulation of autophagosomes in hepatoma cells. However, no autophagic protein degradation was observed, indicating a blockage of autophagic flux at later stages. This inhibition of autophagy flux might be due to an impairment of lysosomal acidification in hepatoma cells. Moreover, HBV-mediated autophagy modulation was independent of the viral subgenotypes and enhanced in viruses with BCP and preCore naturally occurring mutations. These results contribute to understand the mechanisms by which different HBV variants contribute to the pathogenesis of HBV infections. In addition, this study is the first to describe the role that two highly prevalent naturally occurring mutations exert on the modulation of HBV-induced autophagy.

Role of HLA-DP and HLA-DQ on the clearance of hepatitis B virus and the risk of chronic infection in a multiethnic population

BACKGROUND & AIMS

HBV infection exhibits geographical variation in its distribution in South America. While HBV rates are low in central Argentina, the north-western region exhibits intermediate HBV rates. Unfortunately, the reasons that could explain this difference are still unknown.

METHODS

A total of 1440 Argentines were recruited and grouped into HBV patients, HBV-resolved individuals and healthy controls. Genetic ancestry was assessed by analysis of biparental lineages and ancestry autosomal typing. SNPs of HLA-DPA1 (rs3077), HLA-DPB1 (rs9277542), HLA-DQB1 (rs2856718) and HLA-DQB2 (rs7453920) were determined, and HBV genotyping was performed by phylogenetic analysis in HBV patients.

RESULTS

Native American ancestry prevailed in the north-western region when compared with central Argentina (P<.0001). However, no differences were observed among the three groups of each region. The distribution of HBV genotypes revealed significant differences (P<.0001). Three SNPs (rs3077, rs9277542 and rs7453920) showed a significant association with protection against chronic HBV and viral clearance in both regions. The remaining SNP showed a significant association with susceptibility to chronic HBV. The frequency rates of rs3077-T, related to protection against chronic HBV and viral clearance, were lower in north-western Argentina when compared with central Argentina. The same uneven frequency rates were observed for SNP rs9277542.

CONCLUSIONS

This is the first study addressing the associations between the HLA-DP and HLA-DQ loci and the protection against chronic HBV and viral clearance in a multiethnic South American population. The uneven distribution of HLA-DP and HLA-DQ supports the HBV epidemiological differences observed in these two regions of Argentina with dissimilar ancestry genetic background.

HBV DNA genome co-transfection procedure for the evaluation of relative fitness

Hepatitis B virus (HBV) has a high mutation rate and exists as a mixture of genetically different but closely related variants. We present a HBV DNA co-transfection fitness assay and use it to evaluate the relative fitness of different HBV variants in two scenarios: seroconversion process and occupation of an ecological niche. In the seroconversion experiment, subgenotype D1 (sgtD1) deletion (1763-1770) had significantly lower fitness comparing with both sgtD1 wild type and sgtD1mut G1896A, while, in the case of occupation of ecological niche experiment, the results showed the same relative fitness between all of the genotype combinations, except F1b-F4. In this case sgtF1b clearly overgrow sgtF4, which is in accordance with the observation that F1b is the most prevalent in the new infections in Argentina. In summary, we present a method aimed to evaluate HBV viral fitness which improve the analysis of the relative frequency of viral variants during the HBV infection process.

Comparison of Detection Rate and Mutational Pattern of Drug-Resistant Mutations Between a Large Cohort of Genotype B and Genotype C Hepatitis B Virus-Infected Patients in North China

The study aimed to investigate the association of prevalent genotypes in China (HBV/C and HBV/B) with HBV drug-resistant mutations. A total of 13,847 nucleos(t)ide analogue (NA)-treated patients with chronic HBV infection from North China were enrolled. HBV genotypes and resistant mutations were determined by direct sequencing and confirmed by clonal sequencing if necessary. HBV/B, HBV/C, and HBV/D occupied 14.3%, 84.9%, and 0.8% across the study population, respectively. NA usage had no significant difference between HBV/B- and HBV/C-infected patients. Lamivudine-resistant mutations were more frequently detected in HBV/C-infected patients, compared with HBV/B-infected patients (31.67% vs. 25.26%, p < 0.01). Adefovir- and entecavir-resistant mutation detection rates were similar, but the mutational pattern was different between the two genotypes. For adefovir-resistant mutations, HBV/C-infected patients had a higher detection rate of rtA181 V (HBV/C 5.29% vs. HBV/B 1.36%, p < 0.01) and a lower detection rate of rtN236T (2.70% vs. 6.54%, p < 0.01). For entecavir-resistant mutations, HBV/C-infected patients had a higher detection rate of rtM204 V/I+T184 substitution or S202G/C (3.66% vs. 2.16%, p < 0.01) and a lower detection rate of rtM204 V/I+M250 V/I/L substitution (0.67% vs. 1.46%, p < 0.01). Multidrug-resistant mutations (defined as coexistence of mutation to nucleoside and nucleotide analogues) were detected in 104 patients. HBV/C-infected patients had a higher detection rate of multidrug-resistant mutation than HBV/B-infected patients (0.83% vs. 0.35%, p < 0.05). The study for the first time clarified that HBV/C-infected patients had a higher risk to develop multidrug-resistant mutations, compared with HBV/B-infected patients; and HBV/C- and HBV/B-infected patients had different inclinations in the ETV-resistant mutational pattern.

Analysis of the Molecular Evolution of Hepatitis B Virus Genotypes in Symptomatic Acute Infections in Argentina

Hepatitis B virus (HBV) is a globally distributed human pathogen that leads to both self-limited and chronic infections. At least eight genotypes (A-H) with distinct geographical allocations and phylodynamic behaviors have been described. They differ substantially in many virological and probably some clinical parameters. The aim of this study was to analyze full-length HBV genome sequences from individuals with symptomatic acute HBV infections using phylogenetic and coalescent methods. The phylogenetic analysis resulted in the following subgenotype distribution: F1b (52.7%), A2 (18.2%), F4 (18.2%) and A1, B2, D3 and F2a 1.8% each. These results contrast with those previously reported from chronic infections, where subgenotypes F1b, F4, A2 and genotype D were evenly distributed. This differential distribution might be related to recent internal migrations and/or intrinsic biological features of each viral genotype that could impact on the probability of transmission. The coalescence analysis showed that after a diversification process started in the 80s, the current sequences of subgenotype F1b were grouped in at least four highly supported lineages, whereas subgenotype F4 revealed a more limited diversification pattern with most lineages without offspring in the present. In addition, the genetic characterization of the studied sequences showed that only two of them presented mutations of clinical relevance at S codifyng region and none at the polymerase catalytic domains. Finally, since the acute infections could be an expression of the genotypes currently being transmitted to new hosts, the predominance of subgenotype F1b might have epidemiological, as well as, clinical relevance due to its potential adverse disease outcome among the chronic cases.

Molecular epidemiology of hepatitis B virus in Misiones, Argentina

Hepatitis B virus (HBV) infection is a major public health problem worldwide. The aims of this study were to describe the molecular epidemiology of HBV in the Province of Misiones, Argentina and estimate the phylodynamic of the main groups in a Bayesian coalescent framework. To this end, partial or complete genome sequences were obtained from 52 blood donor candidates. The phylogenetic analysis based on partial sequences of S/P region showed a predominance of genotype D (65.4%), followed by genotype F (30.8%) and genotype A as a minority (3.8%). At subgenotype level, the circulation of subgenotypes D3 (42.3%), D2 (13.5%), F1b (11.5%) and F4 (9.6%) was mainly identified. The Bayesian coalescent analysis of 29 complete genome sequences for the main groups revealed that the subgenotypes D2 and D3 had several introductions to the region, with ancestors dating back from 1921 to 1969 and diversification events until the late '70s. The genotype F in Misiones has a more recent history; subgenotype F4 isolates were intermixed with sequences from Argentina and neighboring countries and only one significant cluster dated back in 1994 was observed. Subgenotype F1b isolates exhibited low genetic distance and formed a closely related monophyletic cluster, suggesting a very recent introduction. In conclusion, the phylogenetic and coalescent analyses showed that the European genotype D has a higher circulation, a longer history of diversification and may be responsible for the largest proportion of chronic HBV infections in the Province of Misiones. Genotype F, especially subgenotype F1b, had a more recent introduction and its diversification in the last 20years might be related to its involvement in new transmission events.

Virological Characteristics of Acute Hepatitis B in Eastern India: Critical Differences with Chronic Infection

Hepatitis B Virus (HBV) manifests high genetic variability and is classifiable into ten genotypes (A-J). HBV infection can lead to variable clinical outcomes, ranging from self-limiting acute hepatitis to active chronic hepatitis, cirrhosis and hepatocellular carcinoma. The present study characterizes HBV strains circulating among patients with acute (AHB) and chronic HBV infection (CHB). Among a total of 653 HBsAg positive cases, 40 manifested acute infection. After sequencing the surface(S), basal core promoter/pre-core(BCP/PC) and the X gene regions, phylogenetic tree was constructed using MEGA4 by neighbor-joining method. Statistical robustness was established with bootstrap analysis. Nucleotide diversity was determined by Shannon entropy per site using the Entropy program of the Los Alamos National Laboratories. Analyses of acute patients revealed that HBV/D2 is the major circulating sub-genotype and commonly associated with sexual promiscuity and the age group between15-30 years. Comparison of AHB and CHB patients revealed that HBeAg positivity, ALT levels and genotype D were significantly high in AHB, whereas CHB patients were predominantly male, had a high viral load, and were commonly associated with genotype C. The frequencies of mutations in the S, BCP/PC, and X gene were low in AHB as compared to CHB. Drug resistant mutations were not detectable in the polymerase gene of AHB. Average nucleotide diversity in AHB was considerably low as compared to CHB. Further, the highest average ΔH (average difference in entropy between chronic and acute infection) was observed in the BCP/PC region implying that this region was most vulnerable to mutations upon HBV persistence, especially in case of genotype C. Additionally, among all substitutions, the A1762T and G1764A BCP mutations were the strongest indicators of chronicity. In conclusion, the study exhibits a general portrait of HBV strains circulating among acute hepatitis B patients in Eastern India and their intricate differences with chronic patients which should be useful from the clinical point of view.

G1896A Precore Mutation and Association With HBeAg Status, Genotype and Clinical Status in Patients With Chronic Hepatitis B

BACKGROUND

Precore stop codon (G1896A) mutation is one of the commonest mutations found in patients with chronic hepatitis B. However, over the years, this mutation was not reported much in Malaysia.

OBJECTIVES

We therefore investigated the presence of G1896A mutation in Malaysian population and its association with HBeAg status, clinical stage, hepatitis B virus (HBV) genotype and e-seroconversion rate.

PATIENTS AND METHODS

Serum samples from 93 patients confirmed as hepatitis B carriers were collected for molecular assay. The whole genome of HBV was amplified by polymerase chain reaction and directly sequenced. The precore and basal core promoter regions were analyzed for presence of mutations.

RESULTS

The most commonly observed mutation in the precore region was C1858T with 64.5% prevalence. The precore mutation of interest (G1896A) was identified in 25.8% of isolates. The basal core promoter mutations detected were A1762T-G1764A (26.9%), C1653T (8.6%), A1752G (10.8%) and C1766T (2.2%). No significant association was observed between G1896A mutation and HBeAg-negativity. Nonetheless, G1896A was highly prevalent among HBV genotype B. Clinical association revealed that subjects with G1896A mutations were mainly detected in asymptomatic chronic hepatitis B (58.3%) and liver cirrhosis (41.7%). One subject was diagnosed with fulminant hepatitis (4.2%) and 8.3% had hepatocellular carcinoma (HCC).

CONCLUSIONS

Our data suggested an intermediate prevalence of G1896A mutation among Malaysian hepatitis B carriers. The stop codon mutation has a significant association with genotype B and patients with chronic hepatitis B and liver cirrhosis.